Earnings Per Share (Reconciliation of Net Earnings to Net Earnings Per Share Basic and Diluted) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share
Net earnings	$ 44,798	$ 42,446	$ 68,181	$ 69,814
Basic shares outstanding	66,633	68,737	67,182	68,597
Dilutive effect of stock options and restricted stock	1,272	1,198	1,281	1,234
Diluted shares outstanding	67,905	69,935	68,463	69,831
Basic earnings per share	$ 0.67	$ 0.62	$ 1.01	$ 1.02
Diluted earnings per share	$ 0.66	$ 0.61	$ 1.00	$ 1.00